Samsung 20R Cells

Alright guys this is kind of a weird one but I need to know what the community thinks. I’ve searched around a bit and seem to have found really vary-ing opinions on how these cells perform. So far I’ve learned they sag a lot and that they don’t have an incredible range (2000mAh cells).

Apparently @BillGordon thinks they’re trash

@Skyart didn’t trash them but gave some reasonable specs

I found the same specs online as he did. I couldn’t find a whole lot in other threads about them, so here we are. Lets discuss the 20R. I realize that the 30Q and almost every other cell is better, but I happen to have quite a few salvage 20R cells and I want to know if they’re worth doing anything with.

Some of you may have seen this picture, I have all of these (20 of them are 20Q cells) plus a few extra that have a little bit of rust on the ends. I was planning to not use any that had a single spec of rust on them because I don’t want to risk anything, but there’s 5 or 6 that only have some surface rust on the positive or negative ends.

After seeing that I could make a ~10s7p pack out of these, are they even worth it at that? What kind of range would be feasible? Could I just sand the rust off a few of the ones with only a little surface rust?

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Battery distributors recomend discarding cells that have discolored PVC sleeves, inspect each cell make sure nothing is happening under that plastic sleeve. Especially with the ones that have rust spots. 10s7p is huuuge and heavy, will you be building this batt yourself?

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So I got some 22p (2.1Ah 15a discharge) and made a 12s10p. The sag suuuuuuuuucks. They’d be great for a scooter type vehicle though. But esk8 wise, you’ll hate em.

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you could do what I did with your spare cells and make a back pack range extender.

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No, not worth it

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bike or scooter maybe

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Ah good note. I know that a few did, ones with bad rust on them. I’ll make sure to inspect closely before spot welding or using them.

I will be building it myself, whatever it ends up being.

Personally I would test them out and see how they perform at different currents. With that info I’d try to find the correct application by comparing to other more known cells.

For example Sanyo’s 18650GA’s sag less than 30Q’s until you hit about 7 or 8 Amps per cell. So for any larger packs it’s way more cost effective and it builds a better battery that sag’s less.

They’re not worth it, 25r cells are a relic now and the 20r / 22p cells are even worse.

I had a 22p 10s5p and I got 5v of voltage sag in the middle of the voltage curve, when pulling less than 40a. A 7p pack won’t fare much better

:-1::-1::-1::-1::-1:

E: a comparison graph from lygte of 25r and 20r

Here’s a second graph comparing 20r and 30q:

I know these graphs aren’t exactly indicative of real world performance but it’s as close as you’re gonna get without trying the pack yourself / getting the word of someone who’s built a similar pack :man_shrugging:t2:

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These cells are in a offgrid mobile 230 VAC module in a 7S15P config. Got two of these packs so potentially 14S15P. I have no clue what to do with them atm either. Maybe build a power backup for a friends VW klienbus. 🤷

YES
With one of them fancy Smart BMS’, its hard to go wrong. You see exactly how the pack is performing and if one group starts to get low, pitch it. Also, because a range extender pulls about 5-10 amps total, these cells are on light duty. Put a bunch of saggy cells in there, who cares, lol.
In any case, if this is your first battery, it will be great practice. You got the cells, use them, go ZOOOOM

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Yeah maybe better applied for a different project. Not looking for 10V of sag lol

Ah this is a good idea!

Not sure exactly how this works, but I will read up on it, either way, I like it, didn’t think of that.

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Yeah I get what you’re saying, they’re as good as I’ve got rn.

Yknow maybe I will just make a giant battery bank and use it for camping or something lol

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Jeez where did you get so many cells from? :joy:

Thanks for all the suggestions! These cells seemed to fair pretty well in the packs I got them from, so I guess the previous application doesn’t pull many amps.

I guess now I need to find a way to get them all to storage charge… This should be interesting. Any suggestions on a multi-cell discharger?


Mppt Unit in reverse will discharge a pack with programmable over all voltage and current limits for the source (pictured here, a 10s6p charging a 10s5p)


RC hobby discharger, up to 8s, 200w I think. Automatic.

This last thing is good for 150-200ish W discharge up to 10s I think. I augmented the fans and sinks, maybe good for 300w?

This is what I used to torture the 40ts at 30a discharge. @KfromtheBay Has a stock one.

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Ah very interesting. I never thought of using an MPPT that way lol

Hope you have a nearby bucket of sand haha

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Haha, it was just a single cell and I watched it with thermal cam.

Sounds like fun , Great Scott did a Youtube video a while ago torturing liion packs and it was surprising how calmly some of them reacted to the abuse